Problem: On the first 3 exams of his language class, Ishaan got an average score of 85. What does he need on the next exam to have an overall average of 88?
Explanation: Let his score on the next exam be $x$ The sum of all of his scores is then $3 \cdot 85 + x$ The same sum must also be equal to $4 \cdot 88$ Solve: $x = 4 \cdot 88 - 3 \cdot 85 = 97$.